Interested in open data, particularly public-sector open data? Indulge yourself then in a Desert Island Discs moment. Specifically, that moment at the end of the programme where the interviewee, having picked their seven "must have" songs, is asked which of all of them he or she would keep before all others - the one that they truly must have.

The equivalent version for you is: which set of open data would you like to get from the UK government so as to have the maximum impact on the open data movement?

Obviously, many people reply to this by saying "well, all of it, please". The trouble is that that's not an available answer, given how government and the civil service works. To pararaphrase William Gibson, public sector open data is here, it's just not evenly distributed. Quite possibly it won't ever be, but it is possible to focus which part of it is available by suitable prompting and lobbying. So we need to refine our thinking some more. We can't have it all right now, but we can have some of it now. So, which?

A subsidiary question that people ask is "why are you bringing this up at all? Isn't the open data movement already victorious?" To which the answer is no, not at all.

I recently met some people inside government who are trying to push the open data idea, of getting anonymised, publicly-collected data out there for developers to be able to build applications which will have both financial and societal benefits. It is taken seriously at the top levels of government; they aren't just paying it lip service. The problem though is that there's only so much time available to anyone to push the agenda through. Other change has to be cultural, institutional, and that's where it tends to become difficult: people don't like change if they can't see the benefits.

That's what leads us back to the question at the top. If the people inside the civil service presently labouring with the question of quite why the crime data should be available were able to see its release having a positive effect, or if they could see it being welcomed by the public, perhaps they'd find the cultural change easier to bear. Of course the politicians could help too; I've not heard any anecdotes of ministers coming into their office in the morning and saying to their aides "Fantastic stuff getting that data released! Brilliant work!" Perhaps I haven't been listening hard enough.

Lies, damned lies and statistics

The release of data isn't helped by press releases which distort the truth, such as First Direct's claim in July that "Fear of crime maps hits reporting of crime". This opened with the assertion that "More than 5.2 million* people have not reported crimes for fear of deterring home buyers or renters since the online crime map was launched in February 2011". Oh, that asterisk? "* Consumer Intelligence carried out an online poll of 2,685 UK adults aged 18+ on behalf of Direct Line, 6 – 11 May (5.2 million figure calculation = 10.9 per cent of 48,081,800 UK adult population = 5.2 million)."

Online poll, eh? No data about how people were chosen (or chose) to participate; only lots of up in the air suppositions. The press release is an astonishing bit of presumptions that aren't questioned, but leaves a dangerous feeling behind. It's worth reading, but make sure that when you do, you ask yourself: how do they know that these people who are claimed to not be reporting these crimes now would have reported them before crime maps? In other words, is it actually the existence of crime maps that's putting people off, or is it just some variant of the bystander effect?

Fight of the few

Which takes us to the Open Data Deathmatch. What dataset would be the best one to get released? When I asked this question on Twitter, I got a variety of answers, but they boiled down to a few:

• transport data, including train timetables, prices, and live departure and arrival times. We pay billions of pounds to the rail network and operators - the least we deserve is open data about how to use them to the best effect;

• health data, such as comparative GP data: you need to know about hospitals and GPs and other health provision in your area. You could also find out useful things about local mortality, morbidity and disease rates;

• education data, such as how schools in local areas or places that you (parents) might be looking to move to are performing;

• crime and neighbourhood data

• spending data, from both central and local government, with both geotagging and timing information: we should know when and where and with who the government is spending our money;

• Land Registry data: we should know who owns what parts of the country;

• Companies House data, including the balance sheets and profit & loss accounts for all the companies in the UK.

This is also wrapped up with the Public Data Consultation, which is connected to what will happen to more detailed data from Ordnance Survey, the Met Office, and potentially a number of other agencies. If you haven't responded yet to the public data consultation, you should do so; the deadlines for responses is 22 October 2011.

Where tools like GPS (the most powerful example of government free data generating commercial benefit) excel, and the reason why it is used so widely, is because it solves the problem of "where am I, and how do I get to where I want to get to?" It has that essential predictive quality. We can apply it directly to our lives. So let's weigh up the rivals on that basis.

Predicting your future

•Transport data: Transport for London has seen real excitement over its Countdown system to tell you when buses will arrive at any given stop: for someone who wants to catch a bus, it adds a smattering of certainty to their lives. Transport data definitely has that key predictive ability - if you want to know what time the next train leaves to Edinburgh and where from, and even better if you can find out how much it might cost you, the data is performing a useful predictive role.

•Health data has a less immediate predictive power: because many health effects can take years to show, they're more easily overlooked. And when choosing a hospital for an operation (which is not something most people do, or want to do) we're far more reliant on geography - where the facility with the best combination of proximity and equipment is - than anything else. Health data is like pension data: we tend to overlook it until it's too late. That's because humans are short-term-horizon animals, and public open data probably isn't going to roll back a few million years of evolution.

•Education data is similarly useful, but generally only to parents and teachers (and some ministers). It's also quite widely available; one of the best implementations is/was Schooloscope (which is sadly shutting down). It does have some predictive power - it can tell you what sort of experience your child is going to have at school (or for teachers, what it will be like teaching them).

Don't underestimate the importance to parents of being able to choose a "good" school, for which some will spend remarkable amounts and move house in order to get into the right catchment area. (And there are votes for MPs and councillors in doing the "right" things with schools.) But of course for parents to decide where they ought to move to, they also need to know details about the neighbourhood: the aim is to find that magic combination of good school and cheap housing with low crime. Which leads us on to..

•Crime and neighbourhood data: the big problem with the crime maps from the police is that they are so heroically vague. That's because the Information Commissioner argues that the location of a crime can be "personally identifying information" (PII) which shouldn't be made public. So crimes are "mapped" to vast spaces, rather than the location where they happened. This is understandable for cases of domestic abuse, say, but it's hard to see why something like sexual assaults that happened in a park shouldn't be closely located to the park. That would have predictive value: people would know not to go near that area of the park (and perhaps at that time). Those "location-specific" bits of information are what made chicagocrime.org (which directly mapped crime locations, using the police blotter, in Chicago) back in 2005. That's six years ago and it was better than what we have today.

On neighbourhood data, indices of deprivation or levels of council tax are helpful, but nothing is quite going to beat going to a location and walking around a bit, although indices might help to inform your thinking. (Though if everyone thought that poor performance made somewhere not worth moving to, you'd never get urban renaissances such as Hoxton's rise.)

•Spending data might be helpful in predicting how expensive it will be to live somewhere, but spending data is only really useful in examining what has already happened - by definition, that's what it's about.

•Land Registry data is useful to know who owns what, but quite what it's going to tell you about how your life is going to change (compared, say, to transport data or crime or education data) is hard to see. That's not to say it doesn't have utility - it certainly does. Just not as much immediate utility.

•Companies House data too, is retrospective, but it could be very useful for people who want to know about the health of a business, or the track record of the directors of a company. Again and again it's important to know just what sort of company you're doing business with, and it's surprising that Companies House still charges for something which could be very useful if made free. (There are companies which are paying at one end and making the data free at the other, such as Duedil, although the criticism from some is that it doesn't output open data. (This seems like an excessive criticism; the stream has to stop somewhere.) But it's also a niche, if a potentially extremely profitable one.

Collating it all

So to sum up: it looks to me like transport data is the dataset that will have real resonance with people, and which offers the best chance of a win for the open data movement. We all need to travel, even if it's only trivial distances; we want to know costs, we want to know journey times, we want to know where we are. If we could get the train timetables, fares, and bus routes and fares, made available as open data I think that there would be plenty of enterprising developers who would be able to create apps that would let you take advantage of them.

But let us know your thoughts. Which is the Desert Island Dataset? And what will you say in the Public Data Consultation?